Supporting beam for aircraft landing gears



April 20, 1948. EBERINGER 2,440,068

SUPPORTING BEAM FOR AIRCRAFT LANDING GEARS Filed April 7, 1945 2 Sheets-Sheet 1 IN VEN TOR.

BYGEO/PGE 1 Eff/N65? ATTOANFF April 0, 1948. G. 1;. BERINGER 2,440,068

v SUPPORTING BEAM FOR AIRCRAFT LANDING GEARS Filed April 7, 1945 2 Sheets-Sheet 2 INVENTOR.

GM/P65 55547462? f.%12

A TTO/P/VE) ?atented Apr. 20, 1948 SUPPORTINGBEAMZEQR'AIREGEAFT LANDING GEARS George E Beringera, South Bend; Iiidl, assignor to B'en'dirAviation"Cbrporation, South Bend, Ind., a corporati'orrof Delaware'- ApplicatiomApril 7, 1945, r Serial -No.-- 587,058.-

8*Glaims: (Cl. zit-100')- This invention relates. to.the. construction. of. a supportingbeamfor aircraft .landing'gearg-i. e., the structural: member. by. which thetupperportion of the landinggean is securedsto the -body of the aircraft. Usually-thiss-member. will.- also actas a trunnion duringrotationr oi the landing gear into retracted position.

The present. case. is: primarily. directed. to. the improved article or' product, whereas thewnovel method utilizeda inimakingl the'productr is.- claimed. in application-Serial No..619;943; which-.isia"division of the present application. 7

An object of the present inventionisto pnovide a landing gear supporting,, beamor.v trunnion which. can be. formed: withiewer operations and; less expensively than has-heretoforesbeen. the:

case.

A further object of the. present invention is to provide a landing-gear. supportingbeamtor trunnion which will weighappreciably. less than. similar members heretofore used. I

A still further object; of.- the: present-inventiona.

is to form a landingigearsupporting-beam: or trunnion from. a seamless tuhular. blank, thereby.

obtaining substantial. homogeneity in: the metal 0f the finished product, and. improving; its.

strength characteristics and reliability..

A still furthenand-morespecific, object: of the present invention .is. tout-lime. the-pninciples-zset forth in Dewey Patent No... 2,265,-Z23;;issuedi De cember 9,1941, in shapingmheslanding.gearsup-- porting beam on trunnionifroma-ztubular blank thereby making: it.. possible to control the. wall. thickness. of the beam. or trunnioniandain genr eral, distribute. the metalmost. advantageously:

in affording the required, strength-and. rigidity while maintaining the weight at .a minimum..

Further objects will become. apparent.. during the following. discussion .of ardetailed. exempli'fia' Figure 3' shows ,theimember of Figs. 1?. andi2' after the flatteningoperation .ha'sbeen performed. on the spun or redilced'.tube,. andaften ascen? ter opening has been drilled in the. trunnion and a sleeve insertedtherethrough;

Figure 4 is a plan view. ofj'th'e structure. shown in Figure 3;

Figure-5 is an end view. of 'thest'ructu're shown.

in Figs. .3 and/i;

Figureifi isafron't elevation. showing the com pletedilandinggear assembly, including thetrunnion. of. the; preceding. figures; and

Figure 7 is a plan view of the structureshown inFlgure 6.

The tubular. blank 1?. ofFigurel which is preferably seamless. in order to providehomogeneity 01".. the). metal in..the. finishedtrunnion, is first formed. to..t.he shape shown. in. Figure 2. by the method. described inlDewey Patent 2,265,723,v issuedQDecember 91,. L941. By using. the process ofJ tlie Dewey patent it. is possible to reduce a.

length. of tuhingof. uniform diameter and circular cross-section, as shown in Figure 1, to the desiredouter diameter, while atthe sametime controlling the-thickness of the tube. wall in accordance with thestructurall requirements of the member being. formed. Thisfeature is. particularly. important .in: the. construction of airplane parts,.hecauseit permits the formation of hollow structuralmembers havingithe least possible weight. consistent with strength and rigidity requirements.

Asiillustrated. in Figure 2., the. center. portion 1410f therediwedltube is allowed to retain the original outer diameter for ashortdist'ance. On eachside. oflthe. center! port-ion. I 4 of. the reduced. tube: a taperingportion. I6 is provided which terminates. in. a. relatively small diameter end portion.' l8}. Theshaped tube forms asymmetrical.structure the several. portions of which remain rpai tsof a-nintegral and homogeneous metal structures Becauseof strength requirements, I prefer to increase. the 'wall.:.thicknessof the end. portions l8 slightly over the wallthickness of the-center portion. I4. Howevenit. will. be apparent from the.ditawings. that thedifierence in wall thickness: is.veryslight, and. does not necessarily bear arelation ,to. the reduction. in. outer. diameter. Utilieationottheprocesstdescribed in the aforementioned. Dewey patent makesit; possible to providean. amountof metal at various sections which corresponds. to. the. structural. require.-

ments,.without necessitating. excess weight due to lack of controllability of. the exact. dimensions of. the formed tube... The. importance. of. such weight reduction in. airplane use is.well.recog nl'zed.

In. an ordinary swaging. operation, when an amountotmetalisdisplaced asiaresult of diameter. reduction, it results in a. corresponding. increase in wallv thickness. In other words, the cross-sectional area. remains substantially constant throughout the'swaging; However, .by using the Dewey forming process, it is possible to control the wall thickness as desired, holding it the same, or even decreasing it during the diameter-reduction. In actual practice, in forming the trunnions under discussion, I have found it advisable to increase the wall thickness about twenty-five percent. But this is mentioned by way of illustration, merely.

Furthermore, the use of the tubular blank avoids the necessity for welding or like operations to provide a seam between separately formed half-shells, thereby eliminating expense, and insuring, insofar as possible, sameness of the material throughout.

After the tube has been formed to the shape shown in Figure 2, the center portion l4 and the tapered portions l6 thereof are flattened to provide a substantially elliptical cross-section which or beam to external bending loads acts horizontally, or, in other words, in a direction to counteract the drag load, which is the greatest bending load imposed upon the beam, Furthermore, the maximum horizontal width at the center of the beam enables it to receive the upper end of the airplane landing gear.

For this purpose, aligned openings 20 are provided in the upper and lower walls of the flattened tube. A sleeve 22 is then inserted through the openings 20 and welded as indicated at 24 and 26 to the hollow trunnion or supporting beam. This sleeve provides a member to which the upper end of the landing gear may conveniently be attached, and additionall strengthens the center portion of the beam to aid in resisting the maximum bending moments. Although the center of the trunnion must be sufliciently wide to receive the sleeve 22, it would be a waste of material and would add unnecessary weight to retain this width throughout the length of the trunnion. For this reason the sides of the portions it of the trunnion converge rather sharply, as shown particularly in Fig. 4, until they merge with the end portions [8, which have an inner diameter sufficiently large to receive, after machining of said inner diameter, the members on which the trunnion is supported and which serve as pivots during retraction of the landing gear.

The completed landing gear assembly is shown in Figs. 6 and 7, wherein it will appear that the upper end of the cylindrical upper member 28 of the landing gear shock strut is secured by means of a plurality of bolts 30 to the sleeve 22 which is supported in the trunnion 32. The lower member 34 of the shock strut, which is telescopically arranged within the outer member 28 has mounted thereon the axles 36 arranged to receive the wheels associated with the landing gear.

To provide additional support for the upper member 28 of the shock strut, fittings 38 may be welded to opposite ends of trunnion 32 (a portion of the trunnion ends being cut away for this purpose), and links 40 may connect the fittings 38 to ears 42 welded to strut member 28. The links 40 thus support strut member 28 at a point spaced from the support provided for said strut member by trunnion 32. The links 40 are primarily responsible for withstanding the vertical load on the landing gear due to the weight of the airplane.

An arm 44 is welded to trunnion '32 and is connected at its opposite end to landing gear retraction apparatus. As explained above, the ends of the trunnion are pivotally supported in members which are secured to the body of the airplane. Force exerted through arm 44 therefore rotates trunnion 32 to retract the landing ear.

From the foregoing description, it will be appreciated that the trunnion 32 is a structure sufliciently strong for its purposes and yet having a minimum weight, and is a structure which is especially reliable because of its formation from a homogeneous tubular blank. Furthermore, the steps necessary to form the trunnion 32 are few in number and relatively simple.

Although a particular embodiment of my invention has been described, it will be understood by those skilled in the art that the object of the invention may be attained by the use of constructions difierent in certain respects from that disclosed without departing from the underlying principles of the invention. I therefore desire by the following claims to include within the scope of my invention all such variations and modifications by which substantially the results of my invention may be obtained through the use of substantially the same or equivalent means.

I claim:

1. A supporting beam for an aircraft landin gear comprising a tapered tube having its maximum diameter portion located mid-length of the beam to provide maximum resistance to bending and to accommodate an opening suificiently large to receive the upper end of said landing gear, said tube having reduced diameter cylindrical end portions and having tapered portions on each side of the maximum diameter portion joining it to the end portions,the wall thickness of the end portions being such that the crosssectional area of the annular metal surface in the end portions is appreciably less than the cross-sectional area of the annular metal surface in the maximum diameter portion.

2. A trunnion for an aircraft landing gear comprising a formed andfiattened tube having a substantially elliptical cross-section mid-length of the tube and substantially cylindrical cross-sections at its end portions, the major axis of the elliptical portion being substantially horizontal, said major axis being longest at a point midlength of the'tube and gradually reducing toward the ends of the tube to merge with the cylindrical cross-section at said ends.

3. A trunnion for an aircraft landing gear comprising a formed and flattened tube having a substantially elliptical cross-section mid-length of the tube and substantially cylindrical cross-sections at its end portions, the major axis of the elliptical portion being substantially horizontal, said major axis being longest at a point mid length of the tube and gradually reducing toward the ends. of the tube to merge with the cylindrical cross-section at said ends, the mid-length portion of said tube having a vertical Opening formed therein to receive the upper end of the aircraft landing gear. g

4. A trunnion for an aircraft landing gear comprising a formed and flattened tapered tube having maximum diameter and substantially elliptical cross-section mid-length of the tube and pro gressively reducing in diameter and simultaneously approaching circularity toward each end to merge into cylindrical end portions.

5. A trunnion for an aircraft landing gear comprising a formed and flattened tapered tube having maximum diameter and substantiallyelliptical cross-section mid-length of the tube and progressively reducing in diameter and simultaneously approaching circularity toward each end to merge into cylindrical end portions, the end portions of said tube being adapted to receive cylindrical pivot members about which the trunnion rotates during retraction of the landing gear.

6. A trunnion for an aircraft landing gear comprising a formed and flattened tapered tube having maximum diameter and substantially elliptical cross-section mid-length of the tube and progressively reducing in diameter and simultaneously approaching circularity toward each end to merge into cylindrical end portions, the end portions of said tube being adapted to receive cylindrical pivot members about which the trunnion rotates during retraction of the landing gear, the major diameter of the elliptical mid-length portion of the tube being in a substantially horizontal plane and having an opening therethrough adapted to receive the upper end of the landing gear.

7. An aircraft landing gear assembly including a trunnion comprising a formed and flattened tapered tube having maximum diameter and substantially elliptical cross-section mid-length of the tube and progressively reducing in diameter and simultaneously approaching circularity toward each end to merge into cylindrical end portions, the end portions of said tube being adapted to receive cylindrical pivot members about which the trunnion rotates during retracotally supported at each end on end fittings I mounted on the body of the aircraft, said tube having an appreciable diminution in outside diameter progressing from the mid-length point toward the ends, while having a relatively slight increase in wall thickness such that the crosssectional area of the annular metal surface in the end portions is appreciably less than the cross-sectional area of the annular metal surface in the mid-length portion.

GEORGE E. BERINGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,596,544 Kroesen Aug. 17, 1926 1,652,630 Mogford Dec. 13, 1927 1,781,723 Fox Nov. 18, 1930 2,121,670 Saives June 21, 1938 2,133,091 Gettig Oct. 11, 1938 2,222,683 Overbeke Nov. 26, 1940 2,329,168 Wassall Sept. 7, 1943 

